ITU-T VCEG (Q6/16) and ISO/IEC MPEG (JTC 1/SC 29/WG 11) promulgated the H.265/HEVC (High Efficiency Video Coding) standard in 2013 (version 1), and provided updates in 2014 (version 2), 2015 (version 3), and 2016 (version 4). Since, the ITU has been studying the potential need for standardization of future video coding technology with a compression capability that significantly exceeds that of the HEVC standard (including its extensions).
In October 2017, the ITU issued the Joint Call for Proposals on Video Compression with Capability beyond HEVC (CfP). By Feb. 15, 2018, a total of 22 CfP responses on standard dynamic range (SDR), 12 CfP responses on high dynamic range (HDR), and 12 CfP responses on 360 video categories were submitted, respectively.
In April 2018, all received CfP responses were evaluated in the 122 MPEG/10th JVET (Joint Video Exploration Team—Joint Video Expert Team) meeting. With careful evaluation, JVET formally launched the standardization of next-generation video coding beyond HEVC, i.e., the so-called Versatile Video Coding (VVC). The current version of which is VTM (VVC Test Model), i.e., VTM 1.
As compared to DCT-2, of which the fast methods have been extensively studied, the implementation of DST-7 is still much less efficient than DCT-2. For example, VTM 1 includes matrix multiplication.
In JVET-J0066, a method is proposed to approximate different types of DCTs and DSTs in JEM7 by applying adjustment stages to a transform in the DCT-2 family, which includes DCT-2, DCT-3, DST-2 and DST-3, and the adjustment stage refers to a matrix multiplication using a sparse matrix which requires relatively less operation counts.
In JVET-J001, a method for implementing n-point DST-7 using 2n+1 point Discrete Fourier Transform (DFT) is proposed.